Method of making polymer ammunition having a metal injection molded primer insert

ABSTRACT

The present invention provides a method of making polymer ammunition having a metal injection molded primer insert.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. application Ser. No.14/011,202 entitled “Lightweight Polymer Ammunition Cartridge Casings”filed on Aug. 27, 2013, which is a Divisional of U.S. patent applicationSer. No. 13/292,843 entitled “Lightweight Polymer Ammunition CartridgeCasings” filed on Nov. 9, 2011 which issued as U.S. Pat. No. 8,561,543on Oct. 22, 2013, which claims priority to U.S. Provisional ApplicationSer. No. 61/456,664 entitled “Polymer Case Ammunition and Methods ofManufacturing the Same (diffuser and exacter insert)” filed on Nov. 10,2010. The contents of which are incorporated by reference in theirentirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of ammunition,specifically to compositions of matter and methods of making and usingsubstantially cylindrical inserts made by metal injection molding.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC

None.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with lightweight polymer cartridge casing ammunition.Conventional ammunition cartridge casings for rifles and machine guns,as well as larger caliber weapons, are made from brass, which is heavy,expensive, and potentially hazardous. There exists a need for anaffordable lighter weight replacement for brass ammunition cartridgecases that can increase mission performance and operationalcapabilities. Lightweight polymer cartridge casing ammunition must meetthe reliability and performance standards of existing fielded ammunitionand be interchangeable with brass cartridge casing ammunition inexisting weaponry. Reliable cartridge casings manufacturing requiresuniformity (e.g., bullet seating, bullet-to-casing fit, casing strength,etc.) from one cartridge to the next in order to obtain consistentpressures within the casing during firing prior to bullet and casingseparation to create uniformed ballistic performance. Plastic cartridgecasings have been known for many years but have failed to providesatisfactory ammunition that could be produced in commercial quantitieswith sufficient safety, ballistic, handling characteristics, and survivephysical and natural conditions to which it will be exposed during theammunition's intended life cycle; however, these characteristics havenot been achieved.

For example, U.S. patent application Ser. No. 11/160,682 discloses abase for a cartridge casing body for an ammunition article, the basehaving an ignition device; an attachment device at one end thereof, theattachment device being adapted to the base to a cartridge casing body;wherein the base is made from plastic, ceramic, or a composite material.

U.S. Pat. No. 7,610,858 discloses an ammunition cartridge assembled froma substantially cylindrical polymeric cartridge casing body; and acylindrical polymeric middle body component with opposing first andsecond ends, wherein the first end has a coupling element that is a matefor the projectile-end coupling element and joins the first end of themiddle body component to the second end of the bullet-end component, andthe second end is the end of the casing body opposite the projectile endand has a male or female coupling element; and a cylindrical cartridgecasing head-end component with an essentially closed base end with aprimer hole opposite an open end with a coupling element that is a matefor the coupling element on the second end of the middle body and joinsthe second end of the middle body component to the open end of thehead-end component.

Shortcomings of the known methods of producing plastic or substantiallyplastic ammunition include the possibility of the projectile beingpushed into the cartridge casing, the bullet pull being too light suchthat the bullet can fall out, the bullet pull being too insufficient tocreate sufficient chamber pressure, the bullet pull not being uniformfrom round to round, and portions of the cartridge casing breaking offupon firing causing the weapon to jam or damage or danger whensubsequent rounds are fired or when the casing portions themselvesbecome projectiles. To overcome the above shortcomings, improvements incartridge case design and performance polymer materials are needed.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of making a polymer ammunitionhaving a metal injection molded primer insert comprising by the stepsof: forming a substantially cylindrical metal primer insert by metalinjection molding from a primer insert injection mold, wherein thesubstantially cylindrical metal primer insert comprises a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash aperturepositioned in the primer recess to extend through the bottom surface, aprimer flash aperture groove positioned in the primer recess around theprimer flash aperture and a flange that extends circumferentially aboutan outer edge of the top surface; providing a first polymer compositionfor molding a polymer ammunition cartridge; molding from the firstpolymer composition a substantially cylindrical polymeric middle bodyhaving the substantially cylindrical metal primer insert at a first endand a substantially cylindrical polymeric coupling region at a secondend, wherein the first polymer composition extends over an outer surfaceof the substantially cylindrical metal primer insert to the flange andextends over an interior surface of the substantially cylindricalcoupling region to the primer flash hole aperture, wherein the firstpolymer composition extends from the substantially cylindrical polymericcoupling region to the primer flash hole aperture; forming asubstantially cylindrical polymeric bullet-end component from a secondpolymer composition comprising a bullet aperture opposite a polymericbullet-end coupling that mates to the substantially cylindrical couplingregion; coupling the substantially cylindrical coupling region to thepolymeric bullet-end coupling to form a propellant chamber that extendsfrom the primer flash hole aperture to the bullet aperture; inserting aprimer into the primer recess, wherein the primer is in operablycommunication with the propellant chamber through the primer flash holeaperture; at least partially filling the propellant chamber with apropellant; and frictionally fitting a projectile in the bullet-endaperture, wherein the propellant chamber is enclosed at one end by theprimer and the projectile at the other end.

Further comprising a primer flash aperture groove positioned in theprimer recess around the primer flash aperture and the first polymercomposition extends into the primer flash aperture to form a flash hole.The first polymer composition is the same as the second polymercomposition. The first polymer composition is a ductile polymer. Thefirst polymer composition, the second polymer composition or bothcomprise a nylon polymer. The first polymer composition, the secondpolymer composition or both comprise a fiber-reinforced polymericcomposite. The first polymer composition, the second polymer compositionor both comprise between about 10 and about 70 wt % glass fiber fillers,mineral fillers, or mixtures thereof. The bullet aperture comprises oneor more cannelures formed on an inner circumferential surface of thebullet aperture. The substantially cylindrical coupling region and thepolymeric bullet-end coupling are welded or bonded together. The firstpolymer composition, the second polymer composition or both comprisepolyurethane prepolymer, cellulose, fluoro-polymer, ethyleneinter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyetherimide, polyester elastomer, polyester sulfone, polyphenyl amide,polypropylene, polyvinylidene fluoride or thermoset polyurea elastomer,acrylics, homopolymers, acetates, copolymers,acrylonitrile-butadinen-styrene, thermoplastic fluoro polymers, inomers,polyamides, polyamide-imides, polyacrylates, polyatherketones,polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene,terephthalates, polyether imides, polyether sulfones, thermoplasticpolyimides, thermoplastic polyurethanes, polyphenylene sulfides,polyethylene, polypropylene, polysulfones, polyvinylchlorides, styreneacrylonitriles, polystyrenes, polyphenylene, ether blends, styrenemaleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies,phenolics, unsaturated polyesters, bismaleimides, polyurethanes,silicones, vinylesters, urethane hybrids, polyphenylsulfones, copolymersof polyphenylsulfones with polyethersulfones or polysulfones, copolymersof poly-phenylsulfones with siloxanes, blends of polyphenylsulfones withpolysiloxanes, poly(etherimide-siloxane) copolymers, blends ofpolyetherimides and polysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers. Further comprising a neckpositioned between the bullet aperture and the polymeric bullet-endcoupling. Further comprising one or more internal structures in the neckto support a projectile. The bullet aperture comprises one, two, three,or more annular rings that mate with one, two, three, or morecorresponding annular grooves positioned on the projectile.

The present invention provides a method of making a polymer ammunitionhaving a metal injection molded primer insert comprising by the stepsof: forming a substantially cylindrical metal primer insert by metalinjection molding from a primer insert injection mold, wherein thesubstantially cylindrical metal primer insert comprises a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash aperturepositioned in the primer recess to extend through the bottom surface,and a flange that extends circumferentially about an outer edge of thetop surface; providing a first polymer composition for molding a polymerammunition cartridge; molding from the first polymer composition asubstantially cylindrical polymeric middle body having the substantiallycylindrical metal primer insert at a first end and a substantiallycylindrical polymeric coupling region at a second end, wherein the firstpolymer composition extends over an outer surface of the substantiallycylindrical metal primer insert to the flange and extends over aninterior surface of the substantially cylindrical coupling region to theprimer flash hole aperture, wherein the first polymer compositionextends from the substantially cylindrical polymeric coupling region tothe primer flash hole aperture and into the primer flash aperture grooveto form a flash hole; forming a substantially cylindrical polymericbullet-end component from a second polymer composition comprising abullet aperture opposite a polymeric bullet-end coupling that mates tothe substantially cylindrical coupling region, and a neck positionedbetween the bullet aperture and the polymeric bullet-end coupling;coupling the substantially cylindrical coupling region to the polymericbullet-end coupling to form a propellant chamber that extends from theprimer flash hole aperture to the bullet aperture; inserting a primerinto the primer recess, wherein the primer is in operably communicationwith the propellant chamber through the primer flash hole aperture; atleast partially filling the propellant chamber with a propellant; andfrictionally fitting a projectile in the bullet-end aperture, whereinthe propellant chamber is enclosed at one end by the primer and theprojectile at the other end.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention;

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention;

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the polymer coating over the flash holeaperture;

FIGS. 4a and 4b depict images of a catastrophic failure of the polymericcartridge case of FIG. 3;

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention;

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention;

FIGS. 9a-9h depict the diffuser according to a different embodiment ofthe present invention;

FIG. 10 depicts a perspective view of one embodiment of a substantiallycylindrical primer insert;

FIG. 11 depicts a cross-sectional view of a substantially cylindricalprimer insert according to one embodiment of the present invention;

FIG. 12 depicts a cross-sectional view of the substantially cylindricalprimer insert according to FIG. 11 rotated 90 degrees relative to FIG.5; and

FIGS. 13A-13O depict a perspective view of various different embodimentsof the substantially cylindrical primer insert of the present invention.

FIG. 14 depicts an exploded view of the polymeric cartridge casing;

FIGS. 15A and 15B depict a view of the substantially cylindricalopen-ended polymeric bullet-end having a shoulder forming chamber neckand a bullet; and

FIG. 16 depicts an elevation view of a bullet-end component of thepolymeric cartridge casing; and

FIG. 17 depicts a side, cross-sectional view of a bullet-end componentof the polymeric cartridge casing.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

Reliable cartridge manufacture requires uniformity from one cartridge tothe next in order to obtain consistent ballistic performance. Amongother considerations, proper bullet seating and bullet-to-casing fit isrequired. In this manner, a desired pressure develops within the casingduring firing prior to bullet and casing separation. Historically,bullets employ a cannelure, which is a slight annular depression formedin a surface of the bullet at a location determined to be the optimalseating depth for the bullet. In this manner, a visual inspection of acartridge could determine whether or not the bullet is seated at theproper depth. Once the bullet is inserted into the casing to the properdepth, one of two standard procedures is incorporated to lock the bulletin its proper location. One method is the crimping of the entire end ofthe casing into the cannelure. A second method does not crimp the casingend; rather the bullet is pressure fitted into the casing.

The polymeric ammunition cartridges of the present invention are of acaliber typically carried by soldiers in combat for use in their combatweapons. The present invention is not limited to the described caliberand is believed to be applicable to other calibers as well. Thisincludes various small and medium caliber munitions, including 5.56 mm,7.62 mm, 308, 338, 3030, 3006, and .50 caliber ammunition cartridges, aswell as medium/small caliber ammunition such as 380 caliber, 38 caliber,9 mm, 10 mm, 20 mm, 25 mm, 30 mm, 40 mm, 45 caliber and the like. Thecartridges, therefore, are of a caliber between about 0.05 and about 5inches. Thus, the present invention is also applicable to the sportinggoods industry for use by hunters and target shooters.

One embodiment of the present invention includes a substantiallycylindrical insert mold for making a substantially cylindrical insert bymetal injection molding comprising: a top surface opposite a bottomsurface and a substantially cylindrical coupling element that extendsfrom the bottom surface; a primer recess in the top surface that extendstoward the bottom surface; a primer flash hole positioned in the primerrecess to extend through the bottom surface; and a flange that extendscircumferentially about an outer edge of the top surface.

Still another embodiment includes a method of forming a polymericammunition cartridge by providing a substantially cylindrical inserthaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface, forming a substantially cylindricalpolymeric middle body comprising a substantially cylindrical polymericbullet-end and a substantially cylindrical polymeric coupling endconnected by a powder chamber, connecting the substantially cylindricalpolymeric coupling end to the substantially cylindrical couplingelement; and covering circumferentially an interior surface of theprimer flash hole. The method further includes the step of positioning adiffuser comprising a diffuser flash hole in the primer recess andaligning the diffuser flash hole with the primer flash hole.

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention. A cartridge10 suitable for use with high velocity rifles is shown manufactured witha polymer casing 12 showing a propellant chamber 14 with projectile (notshown) inserted into the forward end opening 16. The polymer casing 12has a substantially cylindrical open-ended polymeric bullet-end 18extending from forward end opening 16 rearward to opposite end 20. Thebullet-end component 18 may be formed with the coupling end 22 formed onthe end 20. The coupling end 22 is shown as a female element, but mayalso be configured as a male element in alternate embodiments of theinvention. The forward end of bullet-end component 18 has a shoulder 24forming chamber neck 26. The bullet-end component typically has a wallthickness between about 0.003 and about 0.200 inches and more preferablybetween about 0.005 and more preferably between about 0.150 inches about0.010 and about 0.050 inches.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Thecoupling element 30, as shown may be configured as a male element,however, all combinations of male and female configurations isacceptable for the coupling elements 30 and the coupling end 22 inalternate embodiments of the invention. The coupling end 22 ofbullet-end component 18 fits about and engages the coupling element 30of a substantially cylindrical insert 32. The substantially cylindricalinsert 32 includes a substantially cylindrical coupling element 30extending from a bottom surface 34 that is opposite a top surface 36.Located in the top surface 36 is a primer recess 38 that extends towardthe bottom surface 34. A primer flash hole 40 is located in the primerflash hole 40 and extends through the bottom surface 34 into thepropellant chamber 14. The coupling end 22 extends the polymer throughthe primer flash hole 40 to form an aperture coating 42 while retaininga passage from the top surface 36 through the bottom surface 34 and intothe propellant chamber 14 to provide support and protection about theprimer flash hole 40. When contacted the coupling end 22 interlocks withthe substantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32and middle body component 28. The polymer casing 12 also has asubstantially cylindrical open-ended middle body component 28. Themiddle body component extends from a forward end opening 16 to thecoupling element 22. The middle body component typically has a wallthickness between about 0.003 and about 0.200 inches and more preferablybetween about 0.005 and more preferably between about 0.150 inches about0.010 and about 0.050 inches. The bullet-end 16, middle body 18 andbottom surface 34 define the interior of propellant chamber 14 in whichthe powder charge (not shown) is contained. The interior volume ofpropellant chamber 14 may be varied to provide the volume necessary forcomplete filling of the chamber 14 by the propellant chosen so that asimplified volumetric measure of propellant can be utilized when loadingthe cartridge. Either a particulate or consolidated propellant can beused.

The substantially cylindrical insert 32 also has a flange 46 cut thereinand a primer recess 38 formed therein for ease of insertion of theprimer (not shown). The primer recess 38 is sized so as to receive theprimer (not shown) in an interference fit during assembly. A primerflash hole 40 communicates through the bottom surface 34 ofsubstantially cylindrical insert 32 into the propellant chamber 14 sothat upon detonation of primer (not shown) the powder in propellantchamber 14 will be ignited.

The projectile (not shown) is held in place within chamber case neck 26at forward opening 16 by an interference fit. Mechanical crimping of theforward opening 16 can also be applied to increase the bullet pullforce. The bullet (not shown) may be inserted into place following thecompletion of the filling of propellant chamber 14. The projectile (notshown) can also be injection molded directly onto the forward opening 16prior to welding or bonding together using solvent, adhesive,spin-welding, vibration-welding, ultrasonic-welding or laser-weldingtechniques. The welding or bonding increases the joint strength so thecasing can be extracted from the hot gun casing after firing at thecook-off temperature.

The bullet-end and bullet components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature. An optional firstand second annular grooves (cannelures) may be provided in thebullet-end in the interlock surface of the male coupling element toprovide a snap-fit between the two components. The cannelures formed ina surface of the bullet at a location determined to be the optimalseating depth for the bullet. Once the bullet is inserted into thecasing to the proper depth to lock the bullet in its proper location.One method is the crimping of the entire end of the casing into thecannelures.

The bullet-end and middle body components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature.

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention. A portion of a cartridge suitable for use with high velocityrifles is shown manufactured with a polymer casing 12 showing apropellant chamber 14. The polymer casing 12 has a substantiallycylindrical opposite end 20. The bullet-end component 18 may be formedwith the coupling end 22 formed on end 20. The coupling end 22 is shownas a female element, but may also be configured as a male element inalternate embodiments of the invention. The middle body component (notshown) is connected to a substantially cylindrical coupling element 30of the substantially cylindrical insert 32. The coupling element 30, asshown may be configured as a male element, however, all combinations ofmale and female configurations is acceptable for the coupling elements30 and the coupling end 22 in alternate embodiments of the invention.The coupling end 22 fits about and engages the coupling element 30 of asubstantially cylindrical insert 32. The substantially cylindricalinsert 32 includes a substantially cylindrical coupling element 30extending from a bottom surface 34 that is opposite a top surface 36.Located in the top surface 36 is a primer recess 38 that extends towardthe bottom surface 34. A primer flash hole 40 is located in the primerrecess 28 and extends through the bottom surface 34 into the propellantchamber 14. The coupling end 22 extends the polymer through the primerflash hole 40 to form an aperture coating 42 while retaining a passagefrom the top surface 36 through the bottom surface 34 and into thepropellant chamber 14 to provide support and protection about the primerflash hole 40. When contacted the coupling end 22 interlocks with thesubstantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32and middle body component 28. The polymer casing 12 also has asubstantially cylindrical open-ended middle body component 28.

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the aperture coating (not shown). Aportion of a cartridge suitable for use with high velocity rifles isshown manufactured with a polymer casing (not shown) showing a powderchamber 14. The polymer casing (not shown) has a substantiallycylindrical opposite end 20. The bullet-end component (not shown) may beformed with the coupling end 22 formed on end 20. The coupling end 22 isshown as a female element, but may also be configured as a male elementin alternate embodiments of the invention. The middle body component(not shown) is connected to a substantially cylindrical coupling element30 of the substantially cylindrical insert 32. The coupling element 30,as shown may be configured as a male element, however, all combinationsof male and female configurations are acceptable for the couplingelements 30 and coupling end 22 in alternate embodiments of theinvention. The coupling end 22 fits about and engages the couplingelement 30 of a substantially cylindrical insert 32. The substantiallycylindrical insert 32 includes a substantially cylindrical couplingelement 30 extending from a bottom surface 34 that is opposite a topsurface 36. Located in the top surface 36 is a primer recess 38 thatextends toward the bottom surface 34. A primer flash hole (not shown) islocated in the primer recess 28 and extends through the bottom surface34 into the powder chamber 14. When contacted the coupling end 22interlocks with the substantially cylindrical coupling element 30,through the coupling element 30 that extends with a taper to a smallerdiameter at the tip (not shown) to form a physical interlock betweensubstantially cylindrical insert 32 also has a flange 46 cut therein andmiddle body component (not shown).

FIGS. 4a and 4b depict images of a catastrophic failure of the polymericcartridge case of FIG. 3. Other polymeric cartridge case was tested andresulted in catastrophic failure with the rounds blowing the magazineout of the weapon and fragmenting the metal insert and lodging thepolymer case in the chamber. The examination of the catastrophic failurerevealed the tearing of the polymer at the top of the insert. As aresult, in some embodiments the height of the insert was reduced by0.020″ to reduce the tearing and frequency of catastrophic failures.Further examination, revealed that the polymer at the flash hole of thebase was separating from the insert. One embodiment locks the polymerinto the flash hole by extending the polymer into the flash hole. Inaddition, the raised area was removed, the diameter of the flash holewas opened, and the primer side was counter bored. Other embodiments mayincorporate all, one, or a combination of 2 or more of these elements tostop the gas from separating the polymer from the insert that wascreating combustion between the insert and the polymer.

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing (notshown) showing a powder chamber 14. The polymer casing (not shown) has asubstantially cylindrical opposite end 20. The bullet-end component 18may be formed with the coupling end 22 formed on end 20. The couplingend 22 is shown as a female element, but may also be configured as amale element in alternate embodiments of the invention. The middle bodycomponent (not shown) is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Thecoupling element 30, as shown may be configured as a male element,however, all combinations of male and female configurations isacceptable for coupling elements 30 and coupling end 22 in alternateembodiments of the invention. The coupling end 22 fits about and engagesthe coupling element 30 of a substantially cylindrical insert 32. Thesubstantially cylindrical insert 32 includes a substantially cylindricalcoupling element 30, extending from a bottom surface 34 that is oppositea top surface 36. Located in the top surface 36 is a primer recess 38that extends toward the bottom surface 34. A primer flash hole 40 islocated in the primer recess 28 and extends through the bottom surface34 into the powder chamber 14. The coupling end 22 extends the polymerthrough the primer flash hole 40 to form an aperture coating 42 whileretaining a passage from the top surface 36 through the bottom surface34 and into the powder chamber 14 to provide support and protectionabout the primer flash hole 40. When contacted the coupling end 22interlocks with the substantially cylindrical coupling element 30,through the coupling element 30 that extends with a taper to a smallerdiameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 also has a flange 46 cut therein andmiddle body component 28. The polymer casing (not shown) also has asubstantially cylindrical open-ended middle body component 28. Thesubstantially cylindrical opposite end 20 or anywhere within the powderchamber 14 may include one or more ribs 48 on the surface. The number ofribs 48 will depend on the specific application and desire of themanufacture but may include 1, 2, 3, 4, 5 6, 7, 8, 9, 10, or more ribs.In the counter bore, the polymer was having difficulty filling this areadue to the fact that the polymer used has fillers in it, and needed tobe reblended during molding. One embodiment includes six ribs 48 tocreate turbulence in the flow of the polymer, thus allowing the materialto fill the counter bore.

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. One embodiment that reduces bellowing of theinsert includes a shortened insert and angled the coupling element 30inside of the insert. In addition, the raised portion of the polymer atthe flash hole was removed, the internal polymer wall was lowered andangled to match the insert and the internal ribs were lengthened.

A portion of a cartridge suitable for use with high velocity rifles isshown manufactured with a polymer casing (not shown) showing a powderchamber 14. The polymer casing (not shown) has a substantiallycylindrical opposite end 20. The bullet-end component (not shown) may beformed with coupling end 22 formed on end 20. The coupling end 22 isshown as a female element, but may also be configured as a male elementin alternate embodiments of the invention. The middle body component(not shown) is connected to a substantially cylindrical coupling element30 of the substantially cylindrical insert 32. The coupling element 30,as shown may be configured as a male element, however, all combinationsof male and female configurations are acceptable for the couplingelements 30 and the coupling end 22 in alternate embodiments of theinvention. The coupling end 22 fits about and engages the couplingelement 30 of a substantially cylindrical insert 32. The substantiallycylindrical insert 32 includes a substantially cylindrical couplingelement 30 extending from a bottom surface 34 that is opposite a topsurface 36. Located in the top surface 36 is a primer recess 38 thatextends toward the bottom surface 34. A primer flash hole 40 is locatedin the primer recess 28 and extends through the bottom surface 34 intothe powder chamber 14. The coupling end 22 extends the polymer throughthe primer flash hole 40 to form an aperture coating 42 while retaininga passage from the top surface 36 through the bottom surface 34 and intothe powder chamber 14 to provide support and protection about the primerflash hole 40. When contacted the coupling end 22 interlocks with thesubstantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32and middle body component 28. The polymer casing (not shown) also has asubstantially cylindrical open-ended middle body component 28. Thesubstantially cylindrical opposite end 20 or anywhere within the powderchamber 14 may include one or more ribs 48 on the surface. The number ofribs 48 will depend on the specific application and desire of themanufacture but may include 1, 2, 3, 4, 5 6, 7, 8, 9, 10, or more ribs.In the counter bore, the polymer was having difficulty filling this areadue to the fact that the polymer used has fillers in it, and needed tobe reblended during molding. One embodiment includes six ribs 48 tocreate turbulence in the flow of the polymer, thus allowing the materialto fill the counter bore. Another embodiment of the present invention isa shortened insert and angled coupling element 30 inside of the insert.In addition, raised portions of the polymer at the flash hole, loweredand angled the internal polymer wall to match the insert and lengthenedthe internal ribs.

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention. The diffuser (not shown) is a device that is used to divertthe affects of the primer off of the polymer and directing it to theflash hole. The affects being the impact from igniting the primer as faras pressure and heat. A cartridge 10 suitable for use with high velocityrifles is shown manufactured with a polymer casing (not shown) showing apowder chamber 14 with projectile (not shown) inserted into the forwardend opening 16. The polymer casing (not shown) has a substantiallycylindrical open-ended polymeric bullet-end 18 extending from forwardend opening 16 rearward to the opposite end 20. The bullet-end component(not shown) may be formed with the coupling end 22 formed on the end 20.The coupling end 22 is shown as a female element, but may also beconfigured as a male element in alternate embodiments of the invention.The forward end of bullet-end component 18 has a shoulder 24 formingchamber neck 26.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Thecoupling element 30, as shown may be configured as a male element,however, all combinations of male and female configurations isacceptable for the coupling elements 30 and the coupling end 22 inalternate embodiments of the invention. The coupling end 22 ofbullet-end component 18 fits about and engages the coupling element 30of a substantially cylindrical insert 32. The substantially cylindricalinsert 32 includes a substantially cylindrical coupling element 30extending from a bottom surface 34 that is opposite a top surface 36.Located in the top surface 36 is a primer recess 38 that extends towardthe bottom surface 34. A primer flash hole 40 is located in the primerrecess 28 and extends through the bottom surface 34 into the powderchamber 14. The coupling end 22 extends the polymer through the primerflash hole 40 to form an aperture coating 42 while retaining a passagefrom the top surface 36 through the bottom surface 34 and into thepowder chamber 14 to provides support and protection about the primerflash hole 40. When contacted the coupling end 22 interlocks with thesubstantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32also has a flange 46 cut therein and middle body component 28. Thepolymer casing 12 also has a substantially cylindrical open-ended middlebody component 28. The middle body component extends from a forward endopening 16 to the coupling element 22. Located in the top surface 36 isa primer recess 38 that extends toward the bottom surface 34 with adiffuser (not shown) positioned in the primer recess 38. The diffuser(not shown) includes a diffuser aperture (not shown) that aligns withthe primer flash hole 40. The diffuser (not shown) is a device that isused to divert the affects of the primer (not shown) off of the polymer.The affects being the impact from igniting the primer as far as pressureand heat to divert the energy of the primer off of the polymer anddirecting it to the flash hole.

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing (notshown) showing a powder chamber 14. The polymer casing (not shown) has asubstantially cylindrical opposite end 20. The bullet-end component (notshown) may be formed with the coupling end 22 formed on the end 20. Thecoupling end (not shown) is shown as a female element, but may also beconfigured as a male element in alternate embodiments of the invention.The middle body component (not shown) is connected to a substantiallycylindrical coupling element 30 of the substantially cylindrical insert32. The coupling element 30, as shown may be configured as a maleelement, however, all combinations of male and female configurations areacceptable for the coupling elements 30 and the coupling end (not shown)in alternate embodiments of the invention. The coupling end (not shown)fits about and engages the coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30 extending from a bottomsurface (not shown) that is opposite a top surface 36. Located in thetop surface 36 is a primer recess 38 that extends toward the bottomsurface (not shown). A primer flash hole 40 extends through the bottomsurface (not shown) into the powder chamber 14. The coupling end (notshown) extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface (not shown) and into the powder chamber 14 toprovides support and protection about the primer flash hole 40. Whencontacted the coupling end (not shown) interlocks with the substantiallycylindrical coupling element 30, through the coupling element 30 thatextends with a taper to a smaller diameter at the tip 44 to form aphysical interlock between substantially cylindrical insert 32 also hasa flange 46 cut therein and middle body component 28. The polymer casing(not shown) also has a substantially cylindrical open-ended middle bodycomponent 28. Located in the top surface 36 is a primer recess 38 thatextends toward the bottom surface (not shown) with a diffuser 50positioned in the primer recess 38. The diffuser (not shown) includes adiffuser aperture 52 and a diffuser aperture extension 54 that alignswith the primer flash hole 40. The diffuser 50 is a device that is usedto divert the affects of the primer (not shown) off of the polymer. Theaffects being the impact from igniting the primer as far as pressure andheat to divert the energy of the primer off of the polymer and directingit to the flash hole. The diffuser 50 can be between 0.004 to 0.010inches in thickness and made from half hard brass. For example, thediffuser 50 can be between 0.005 inches thick for a 5.56 diffuser 50.The outer diameter of the diffuser for a 5.56 or 223 case is 0.173 andthe inner diameter is 0.080. The Diffuser could be made of any materialthat can withstand the energy from the ignition of the primer. Thiswould include steel, stainless, cooper, aluminum or even an engineeredresin that was injection molded or stamped. The Diffuser can be producein T shape by drawing the material with a stamping and draw die. In theT Diffuser the center ring can be 0.005 to 0.010 tall and the outerdiameter is 0.090 and the inner diameter 0.080.

FIGS. 9a-9h depict different embodiment of the diffuser of the presentinvention.

FIG. 10 depicts a perspective view of a substantially cylindrical primerinsert according to one embodiment of the present invention. Thesubstantially cylindrical primer insert 32 has an optional flange 46 cuttherein and a primer recess (not shown) formed therein for ease ofinsertion of the primer recess (not shown). The flange 46 extendscircumferentially about the outer edge of the substantially cylindricalprimer insert 32. The primer recess (not shown) is sized so as toreceive the primer in an interference fit during assembly. A series ofnotches 42 are placed along the exterior circumference of substantiallycylindrical primer insert 32 circling the primer recess (not shown)between flange 46 and coupling element 30. The coupling element 30extends from a bottom surface (not shown) to a coupling tip 44. Thedesign, shape and number of notches 42 will depend on the specificapplication and desire of the manufacture but may include 1, 2, 3, 4, 56, 7, 8, 9, 10, or more notches.

FIG. 11 depicts a cross-sectional view of a substantially cylindricalprimer insert 32 according to one embodiment of the present invention.The substantially cylindrical primer insert 32 has a flange 46 cut thatextends circumferentially about an outer edge of the top surface 36. Aprimer recess 38 in the top surface 36 extends from top surface 36towards a bottom surface 34. The substantially cylindrical primer insert32 also includes a coupling element 30 that extends from the bottomsurface 34 to a coupling tip 44. A primer flash hole 40 is positioned inthe primer recess 38 and extends through the bottom surface 34 into aninsert opening 48 in the coupling element 30. When contacted with therest of the cartridge (not shown), the cartridge interlocks with thecoupling element 30.

The metal injection molding process of making the substantiallycylindrical primer insert 32 mold shown is made in the shape of thesubstantially cylindrical primer insert 32 includes the desired profileof the primer recess 38. The substantially cylindrical primer insert 32includes a coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole38 is located in the substantially cylindrical primer insert 32 andextends through the bottom surface 34 into the insert opening 48.

FIG. 12 depicts a rotated, cross-sectional view of a portion of thesubstantially cylindrical primer insert 32 according to one embodimentof the present invention. The substantially cylindrical primer insert 32has a flange 46 cut that extends circumferentially about an outer edgeof the top surface 36. A primer recess 38 in the top surface 36 extendsfrom top surface 36 towards a bottom surface 34. A notch 42 adjacent tothe primer recess 38 extends from flange 46 towards bottom surface 34.The gas generator insert 32 also includes a coupling element 30 thatextends from the bottom surface 34 to a coupling tip 44. A primer flashhole 40 is positioned in the primer recess 38 and extends through thebottom surface 34 into an insert opening 48.

FIGS. 13A-13O depict perspective views of a substantially cylindricalprimer inserts according to various embodiments of the presentinvention. FIGS. 13A-13O illustrate the shape of the substantiallycylindrical primer insert; however other shapes and variations arecontemplated. The flange on the substantially cylindrical primer insertis optional and the notches can be of any number, shape, or designincluding scallop shaped, wing shaped, prism shaped, rectangular shapedand the like.

FIG. 13A shows a perspective view of an embodiment of the substantiallycylindrical primer insert 32 wherein the notches 42 is a triangularprism extending from flange 46 towards bottom surface 34 (not shown).FIG. 13B shows another embodiment of substantially cylindrical primerinsert 32 with an increased number of notches 42 as triangular prismspositioned on flange 46. The number of notches 42 can be tailored to thespecific application and need of the manufacturer.

FIG. 13C shows a perspective view of an embodiment of the substantiallycylindrical primer insert 32 wherein the notches 42 are redesigned as aband 50. Band 50 provides the same lateral support as notches 42 aroundthe primer recess 38 (not shown) and is also positioned on flange 46.

FIG. 13D shows a perspective view of an embodiment of the substantiallycylindrical primer insert 32 wherein the notches 42 are redesigned intothe shape of a laterally extruded half cylinder. The notches 42 arepositioned on flange 46 and extend toward bottom surface 34 (not shown).FIGS. 13E and 13F show additional variations embodiment of thesubstantially cylindrical primer insert 32 with different numbers ofnotches 42 positioned on flange 46. The different embodiments showdifferent spacing between each of the notches 42. The number of notches42 and the spacing between each of them can be tailored to the specificapplication.

FIG. 13G shows a perspective view of another embodiment of thesubstantially cylindrical primer insert 32 with wider laterally extrudedhalf cylinder notches 42 positioned on flange 46. The size and design ofthe notches 42 as well as its placement and the spacing between them canbe tailored to the specific application.

FIG. 13H shows a perspective view of another embodiment of asubstantially cylindrical primer insert 32 where the notches 42 arescallop shaped and continuous. There is no spacing between the series ofconnected notches 42 positioned on top of flange 46. The connectedscallop shaped notches 42 surround the outer casing of the primer recess38 (not shown). FIG. 13I shows another embodiment of the substantiallycylindrical primer insert 32 with continuous scallop notches 42 with adifferent number of scallop notches 42 positioned on flange 46. Thenumber and width of notches 42 can be tailored to the specificapplication.

FIGS. 13J and 13K show a perspective view of different embodiment of thesubstantially cylindrical primer insert 32 wherein the notches 42 arescallop shaped and continuous, but the coupling element 30 are ofvarying lengths or height. FIG. 13J shows an embodiment with a shortercoupling element 30. FIG. 13K shows an embodiment with a taller couplingelement 30 of the substantially cylindrical primer insert. The height orlength of coupling element 30 can be tailored to the specificapplication and need.

FIG. 13L shows another embodiment of the substantially cylindricalprimer insert 32 wherein the notches 42 is scallop shaped andcontinuous, but has a smaller curvature profile. The size, length,numbering, and curvature of the notches 42 can be tailored to thespecific application and need.

FIG. 13M shows another embodiment of the substantially cylindricalprimer insert 32 wherein there are no notches 42 positioned on flange46.

FIG. 13N shows another embodiment of the substantially cylindricalprimer insert 32 wherein notches 42 are replaced by band 50, but band 50includes a series of bands with different profiles and heights. Thethickness, number, height, and profile of band 50 positioned on flange46 and wrapping around primer recess 38 (not shown) can be tailored tothe specific application and need of the manufacturer.

FIG. 13O shows another embodiment of the substantially cylindricalprimer insert 32 wherein notches 42 are a series of different shapeswith different thicknesses and designs, as well as different spacing inbetween each and no set number when positioned on flange 46. The number,shape, design, and spacing of notches 42 can be tailored to the specificapplication and is not limited to recurring similar shapes or designs.

Another embodiment of the present invention having a top surfaceopposite a bottom surface and a coupling element that extends from thebottom surface away from the top surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash holepositioned in the primer recess to extend through the bottom surface,and a flange that extends circumferentially about an outer edge of thetop surface.

For example, the metal injection molding process, which generallyinvolves mixing fine metal powders with binders to form a feedstock thatis injection molded into a closed mold, may be used to form asubstantially cylindrical insert. After ejection from the mold, thebinders are chemically or thermally removed from the substantiallycylindrical insert so that the part can be sintered to high density.During the sintering process, the individual metal particlesmetallurgically bond together as material diffusion occurs to removemost of the porosity left by the removal of the binder.

The raw materials for metal injection molding are metal powders and athermoplastic binder. There are at least two Binders included in theblend, a primary binder and a secondary binder. This blended powder mixis worked into the plasticized binder at elevated temperature in akneader or shear roll extruder. The intermediate product is theso-called feedstock. It is usually granulated with granule sizes ofseveral millimeters. In metal injection molding, only the binders areheated up, and that is how the metal is carried into the mold cavity.

In preparing a feedstock, it is important first to measure the actualdensity of each lot of both the metal powders and binders. This isextremely important especially for the metal powders in that each lotwill be different based on the actual chemistry of that grade of powder.For example, 316L is comprised of several elements, such as Fe, Cr, Ni,Cu, Mo, P, Si, S and C. In order to be rightfully called a 316L, each ofthese elements must meet a minimum and maximum percentage weightrequirement as called out in the relevant specification. Tables I-IVbelow provide other examples of the elemental compositions of some ofthe metal powders, feed stocks, metals, alloys and compositions of thepresent invention. Hence the variation in the chemistry within thespecification results in a significant density variation within theacceptable composition range. Depending on the lot received from thepowder producer, the density will vary depending on the actual chemistryreceived.

TABLE I Material Designation Chemical Composition, %-Low-Alloy SteelsCode Fe Ni Mo C Si (max) MIM-2200⁽¹⁾ Bal 1.5-2.5 0.5 max 0.1 max 1.0MIM-2700 Bal 6.5-8.5 0.5 max 0.1 max 1.0 MIM-4605⁽²⁾ Bal 1.5-2.5 0.2-0.50.4-0.6 1.0

TABLE II Material Designation Chemical Composition, % - Stainless SteelsCode Fe Ni Cr Mo C Cu Nb + Ta Mn (max) Si (max) MIM-316L Bal. 10-1416-18 2-3 0.03 max — — 2.0 1.0 MIM-420 Bal. — 12-14 — 0.15-0.4 — — 1.01.0 MIM-430L Bal. — 16-18 — 0.05 max — — 1.0 1.0 MIM-17-4 PH Bal. 3-515.5-17.5 — 0.07 max 3-5 0.15-0.45 1.0 1.0

TABLE III Material Designation Chemical Composition, % - Soft-MagneticAlloys Code Fe Ni Cr Co Si C (max) Mn V MIM-2200 Bal. 1.5-2.5 — — 1.0max 0.1 — — MIM-Fe-3% Si Bal. — — — 2.5-3.5 0.05 — — MIM-Fe50% Ni Bal.49-51 — — 1.0 max 0.05 — — MIM-Fe50% Co Bal. — — 48-50 1.0 max 0.05 —2.5 max MIM-430L Bal. — 16-18 — 1.0 max 0.05 1.0 max —

TABLE IV Nominal Chemical Composition, % - Controlled-Expansion AlloysMaterial Mn Si C Al Mg Zr Ti Cu Cr Mo Designation Fe Ni Co max max maxmax max max max max max max MIM-F15 Bal. 29 17 0.50 0.20 0.04 0.10 0.100.10 0.10 0.20 0.20 0.20

In addition to the specific compositions listed herein, the skillartisan recognizes the elemental composition of common commercialdesignations used by feedstock manufacturers and processors, e.g.,C-0000 Copper and Copper Alloys; CFTG-3806-K Diluted Bronze Bearings;CNZ-1818 Copper and Copper Alloys; CNZP-1816 Copper and Copper Alloys;CT-1000 Copper and Copper Alloys; CT-1000-K Bronze Bearings; CTG-1001-KBronze Bearings; CTG-1004-K Bronze Bearings; CZ-1000 Copper and CopperAlloys; CZ-2000 Copper and Copper Alloys; CZ-3000 Copper and CopperAlloys; CZP-1002 Copper and Copper Alloys; CZP-2002 Copper and CopperAlloys; CZP-3002 Copper and Copper Alloys; F-0000 Iron and Carbon Steel;F-0000-K Iron and Iron-Carbon Bearings; F-0005 Iron and Carbon Steel;F-0005-K Iron and Iron-Carbon Bearings; F-0008 Iron and Carbon Steel;F-0008-K Iron and Iron-Carbon Bearings; FC-0200 Iron-Copper and CopperSteel; FC-0200-K Iron-Copper Bearings; FC-0205 Iron-Copper and CopperSteel; FC-0205-K Iron-Copper-Carbon Bearings; FC-0208 Iron-Copper andCopper Steel; FC-0208-K Iron-Copper-Carbon Bearings; FC-0505 Iron-Copperand Copper Steel; FC-0508 Iron-Copper and Copper Steel; FC-0508-KIron-Copper-Carbon Bearings; FC-0808 Iron-Copper and Copper Steel;FC-1000 Iron-Copper and Copper Steel; FC-1000-K Iron-Copper Bearings;FC-2000-K Iron-Copper Bearings; FC-2008-K Iron-Copper-Carbon Bearings;FCTG-3604-K Diluted Bronze Bearings; FD-0200 Diffusion-Alloyed Steel;FD-0205 Diffusion-Alloyed Steel; FD-0208 Diffusion-Alloyed Steel;FD-0400 Diffusion-Alloyed Steel; FD-0405 Diffusion-Alloyed Steel;FD-0408 Diffusion-Alloyed Steel; FF-0000 Soft-Magnetic Alloys; FG-0303-KIron-Graphite Bearings; FG-0308-K Iron-Graphite Bearings; FL-4005Prealloyed Steel; FL-4205 Prealloyed Steel; FL-4400 Prealloyed Steel;FL-4405 Prealloyed Steel; FL-4605 Prealloyed Steel; FL-4805 PrealloyedSteel; FL-48105 Prealloyed Steel; FL-4905 Prealloyed Steel; FL-5208Prealloyed Steel; FL-5305 Prealloyed Steel; FLC-4608 Sinter-HardenedSteel; FLC-4805 Sinter-Hardened Steel; FLC-48108 Sinter-Hardened Steel;FLC-4908 Sinter-Hardened Steel; FLC2-4808 Sinter-Hardened Steel;FLDN2-4908 Diffusion-Alloyed Steel; FLDN4C2-4905 Diffusion-AlloyedSteel; FLN-4205 Hybrid Low-Alloy Steel; FLN-48108 Sinter-Hardened Steel;FLN2-4400 Hybrid Low-Alloy Steel; FLN2-4405 Hybrid Low-Alloy Steel;FLN2-4408 Sinter-Hardened Steel; FLN2C-4005 Hybrid Low-Alloy Steel;FLN4-4400 Hybrid Low-Alloy Steel; FLN4-4405 Hybrid Low-Alloy Steel;FLN4-4408 Sinter Hardened Steel; FLN4C-4005 Hybrid Low-Alloy Steel;FLN6-4405 Hybrid Low-Alloy Steel; FLN6-4408 Sinter-Hardened Steel;FLNC-4405 Hybrid Low-Alloy Steel; FLNC-4408 Sinter-Hardened Steel;FN-0200 Iron-Nickel and Nickel Steel; FN-0205 Iron-Nickel and NickelSteel; FN-0208 Iron-Nickel and Nickel Steel; FN-0405 Iron-Nickel andNickel Steel; FN-0408 Iron-Nickel and Nickel Steel; FN-5000Soft-Magnetic Alloys; FS-0300 Soft-Magnetic Alloys; FX-1000Copper-Infiltrated Iron and Steel; FX-1005 Copper-Infiltrated Iron andSteel; FX-1008 Copper-Infiltrated Iron and Steel; FX-2000Copper-Infiltrated Iron and Steel; FX-2005 Copper-Infiltrated Iron andSteel; FX-2008 Copper-Infiltrated Iron and Steel; FY-4500 Soft-MagneticAlloys; FY-8000 Soft-Magnetic Alloys; P/F-1020 Carbon Steel PF; P/F-1040Carbon Steel PF; P/F-1060 Carbon Steel PF; P/F-10C40 Copper Steel PF;P/F-10050 Copper Steel PF; P/F-10060 Copper Steel PF; P/F-1140 CarbonSteel PF; P/F-1160 Carbon Steel PF; P/F-11C40 Copper Steel PF; P/F-11050Copper Steel PF; P/F-11060 Copper Steel PF; P/F-4220 Low-Alloy P/F-42XXSteel PF; P/F-4240 Low-Alloy P/F-42XX Steel PF; P/F-4260 Low-AlloyP/F-42XX Steel PF; P/F-4620 Low-Alloy P/F-46XX Steel PF; P/F-4640Low-Alloy P/F-46XX Steel PF; P/F-4660 Low-Alloy P/F-46XX Steel PF;P/F-4680 Low-Alloy P/F-46XX Steel PF; SS-303L Stainless Steel—300 SeriesAlloy; SS-303N1 Stainless Steel—300 Series Alloy; SS-303N2 StainlessSteel—300 Series Alloy; SS-304H Stainless Steel—300 Series Alloy;SS-304L Stainless Steel—300 Series Alloy; SS-304N1 Stainless Steel—300Series Alloy; SS-304N2 Stainless Steel—300 Series Alloy; SS-316HStainless Steel—300 Series Alloy; SS-316L Stainless Steel—300 SeriesAlloy; SS-316N1 Stainless Steel—300 Series Alloy; SS-316N2 StainlessSteel—300 Series Alloy; SS-409L Stainless Steel—400 Series Alloy;SS-409LE Stainless Steel—400 Series Alloy; SS-410 Stainless Steel—400Series Alloy; SS-410L Stainless Steel—400 Series Alloy; SS-430LStainless Steel—400 Series Alloy; SS-430N2 Stainless Steel—400 SeriesAlloy; SS-434L Stainless Steel—400 Series Alloy; SS-434LCb StainlessSteel—400 Series Alloy; and SS-434N2 Stainless Steel—400 Series Alloy.

One embodiment of the substantially cylindrical metal primer insert mayinclude a composition where Ni may be 2.0, 2.25, 2.50, 2.75, 3.0, 3.25,3.5, 3.75, 4.0, 4.25, 4.50, 4.75, 5.0, 5.25, 5.5, 5.75, 6.0, 6.25, 6.50,6.75, 7.0, 7.25, 7.5, 7.75, 8.0, 8.25, 8.50, 8.75, 9.0, 9.25, 9.5, 9.75,10.0, 10.25, 10.50, 10.75, 11.0, 11.25, 11.5, 11.75, 12.0, 12.25, 12.50,12.75, 13.0, 13.25, 13.5, 13.75, 14.0, 14.25, 14.50, 14.75, 15.0, 15.25,15.5, 15.75, 16.0, 16.25, 16.50, 16.75, or 17.0%; Cr may be 9.0, 9.25,9.5, 9.75, 10.0, 10.25, 10.50, 10.75, 11.0, 11.25, 11.5, 11.75, 12.0,12.25, 12.50, 12.75, 13.0, 13.25, 13.5, 13.75, 14.0, 14.25, 14.50,14.75, 15.0, 15.25, 15.5, 15.75, 16.0, 16.25, 16.50, 16.75, 17.0, 17.25,17.5, 17.75, 18.0, 18.25, 18.50, 18.75, 19.0, 19.25, 19.5, 19.75, or20.0%; Mo may be 0.00, 0.025, 0.050, 0.075, 0.10, 0.125, 0.150, 0.175,0.20, 0.225, 0.250, 0.275, 0.30, 0.325, 0.350, 0.375, 0.40, 0.425,0.450, 0.475, 0.50, 0.525, 0.550, 0.575, 0.60, 0.625, 0.650, 0.675,0.70, 0.725, 0.750, 0.775, 0.80, 0.825, 0.850, 0.875, 0.90, 0.925,0.950, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.50, 2.75, 3.0, 3.25, 3.5,3.75, 4.0, 4.25, 4.50, 4.75, 5.0, 5.25, 5.5, 5.75, 6.0, 6.25, 6.50,6.75, or 7.0%; C may be 0.00, 0.025, 0.050, 0.075, 0.10, 0.125, 0.150,0.175, 0.20, 0.225, 0.250, 0.275, 0.30, 0.325, 0.350, 0.375, 0.40,0.425, 0.450, 0.475, 0.50, 0.525, 0.550, 0.575, 0.60, 0.625, 0.650,0.675, 0.70, 0.725, 0.750, 0.775, 0.80, 0.825, 0.850, 0.875, 0.90,0.925, 0.950, or 1.00%; Cu may be 0.00, 0.025, 0.050, 0.075, 0.10,0.125, 0.150, 0.175, 0.20, 0.225, 0.250, 0.275, 0.30, 0.325, 0.350,0.375, 0.40, 0.425, 0.450, 0.475, 0.50, 0.525, 0.550, 0.575, 0.60,0.625, 0.650, 0.675, 0.70, 0.725, 0.750, 0.775, 0.80, 0.825, 0.850,0.875, 0.90, 0.925, 0.950, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.50, 2.75,3.0, 3.25, 3.5, 3.75, 4.0, 4.25, 4.50, 4.75, 5.0, 5.25, 5.5, 5.75, 6.0,6.25, 6.50, 6.75, 7.0, 7.25, 7.5, 7.75, or 8.0%; Nb+Ta may be 0.00,0.025, 0.050, 0.075, 0.10, 0.125, 0.150, 0.175, 0.20, 0.225, 0.250,0.275, 0.30, 0.325, 0.350, 0.375, 0.40, 0.425, 0.450, 0.475, 0.50,0.525, 0.550, 0.575, 0.60, 0.625, 0.650, 0.675, 0.70, 0.725, 0.750,0.775, or 0.80%; Mn may be 0.00, 0.025, 0.050, 0.075, 0.10, 0.125,0.150, 0.175, 0.20, 0.225, 0.250, 0.275, 0.30, 0.325, 0.350, 0.375,0.40, 0.425, 0.450, 0.475, 0.50, 0.525, 0.550, 0.575, 0.60, 0.625,0.650, 0.675, 0.70, 0.725, 0.750, 0.775, 0.80, 0.825, 0.850, 0.875,0.90, 0.925, 0.950, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.50, 2.75, 3.0,3.25, 3.5, 3.75, 4.0, 4.25, 4.50, 4.75, 5.0, 5.25, 5.5, 5.75, or 6.0%;Si may be 0.00, 0.025, 0.050, 0.075, 0.10, 0.125, 0.150, 0.175, 0.20,0.225, 0.250, 0.275, 0.30, 0.325, 0.350, 0.375, 0.40, 0.425, 0.450,0.475, 0.50, 0.525, 0.550, 0.575, 0.60, 0.625, 0.650, 0.675, 0.70,0.725, 0.750, 0.775, 0.80, 0.825, 0.850, 0.875, 0.90, 0.925, 0.950, 1.0,1.25, 1.5, 1.75, 2.0, 2.25, 2.50, 2.75, 3.0, 3.25, 3.5, 3.75, or 4.0%;and the balance Fe. For example, one embodiment of the substantiallycylindrical metal primer insert may include any amount in the range of2-16% Ni; 10-20% Cr; 0-5% Mo; 0-0.6% C; 0-6.0% Cu; 0-0.5% Nb+Ta; 0-4.0%Mn; 0-2.0% Si and the balance Fe. One embodiment of the substantiallycylindrical metal primer insert may include any amount in the range of2-6% Ni; 13.5-19.5% Cr; 0-0.10% C; 1-7.0% Cu; 0.05-0.65% Nb+Ta; 0-3.0%Mn; 0-3.0% Si and the balance Fe. One embodiment of the substantiallycylindrical metal primer insert may include any amount in the range of3-5% Ni; 15.5-17.5% Cr; 0-0.07% C; 3-5.0% Cu; 0.15-0.45% Nb+Ta; 0-1.0%Mn; 0-1.0% Si and the balance Fe. One embodiment of the substantiallycylindrical metal primer insert may include any amount in the range of10-14% Ni; 16-18% Cr; 2-3% Mo; 0-0.03% C; 0-2% Mn; 0-1% Si and thebalance Fe. One embodiment of the substantially cylindrical metal primerinsert may include any amount in the range of 12-14% Cr; 0.15-0.4% C;0-1% Mn; 0-1% Si and the balance Fe. One embodiment of the substantiallycylindrical metal primer insert may include any amount in the range of16-18% Cr; 0-0.05% C; 0-1% Mn; 0-1% Si and the balance Fe.

Titanium alloys that may be used in this invention include any alloy ormodified alloy known to the skilled artisan including titanium grades5-38 and more specifically titanium grades 5, 9, 18, 19, 20, 21, 23, 24,25, 28, 29, 35, 36 or 38. Grades 5, 23, 24, 25, 29, 35, or 36 annealedor aged; Grades 9, 18, 28, or 38 cold-worked and stress-relieved orannealed; Grades 9, 18, 23, 28, or 29 transformed-beta condition; andGrades 19, 20, or 21 solution-treated or solution-treated and aged.Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the mostcommonly used alloy. It has a chemical composition of 6% aluminum, 4%vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remaindertitanium. It is significantly stronger than commercially pure titaniumwhile having the same stiffness and thermal properties (excludingthermal conductivity, which is about 60% lower in Grade 5 Ti than in CPTi); Grade 6 contains 5% aluminium and 2.5% tin. It is also known asTi-5Al-2.5Sn. This alloy has good weldability, stability and strength atelevated temperatures; Grade 7 and 7H contains 0.12 to 0.25% palladium.This grade is similar to Grade 2. The small quantity of palladium addedgives it enhanced crevice corrosion resistance at low temperatures andhigh pH; Grade 9 contains 3.0% aluminium and 2.5% vanadium. This gradeis a compromise between the ease of welding and manufacturing of the“pure” grades and the high strength of Grade 5; Grade 11 contains 0.12to 0.25% palladium; Grade 12 contains 0.3% molybdenum and 0.8% nickel;Grades 13, 14, and 15 all contain 0.5% nickel and 0.05% ruthenium; Grade16 contains 0.04 to 0.08% palladium; Grade 16H contains 0.04 to 0.08%palladium; Grade 17 contains 0.04 to 0.08% palladium; Grade 18 contains3% aluminum, 2.5% vanadium and 0.04 to 0.08% palladium; Grade 19contains 3% aluminum, 8% vanadium, 6% chromium, 4% zirconium, and 4%molybdenum; Grade 20 contains 3% aluminum, 8% vanadium, 6% chromium, 4%zirconium, 4% molybdenum and 0.04% to 0.08% palladium; Grade 21 contains15% molybdenum, 3% aluminum, 2.7% niobium, and 0.25% silicon; Grade 23contains 6% aluminum, 4% vanadium, 0.13% (maximum) Oxygen; Grade 24contains 6% aluminum, 4% vanadium and 0.04% to 0.08% palladium. Grade 25contains 6% aluminum, 4% vanadium and 0.3% to 0.8% nickel and 0.04% to0.08% palladium; Grades 26, 26H, and 27 all contain 0.08 to 0.14%ruthenium; Grade 28 contains 3% aluminum, 2.5% vanadium and 0.08 to0.14% ruthenium; Grade 29 contains 6% aluminum, 4% vanadium and 0.08 to0.14% ruthenium; Grades 30 and 31 contain 0.3% cobalt and 0.05%palladium; Grade 32 contains 5% aluminum, 1% tin, 1% zirconium, 1%vanadium, and 0.8% molybdenum; Grades 33 and 34 contain 0.4% nickel,0.015% palladium, 0.025% ruthenium, and 0.15% chromium; Grade 35contains 4.5% aluminum, 2% molybdenum, 1.6% vanadium, 0.5% iron, and0.3% silicon; Grade 36 contains 45% niobium; Grade 37 contains 1.5%aluminum; and Grade 38 contains 4% aluminum, 2.5% vanadium, and 1.5%iron. Its mechanical properties are very similar to Grade 5, but hasgood cold workability similar to grade 9. One embodiment includes aTi6Al4V composition. One embodiment includes a composition having 3-12%aluminum, 2-8% vanadium, 0.1-0.75% iron, 0.1-0.5% oxygen, and theremainder titanium. More specifically, about 6% aluminum, about 4%vanadium, about 0.25% iron, about 0.2% oxygen, and the remaindertitanium. For example, one Ti composition may include 10 to 35% Cr, 0.05to 15% Al, 0.05 to 2% Ti, 0.05 to 2% Y2O5, with the balance being eitherFe, Ni or Co, or an alloy consisting of 20±1.0% Cr, 4.5±0.5% Al,0.5±0.1% Y2O5 or ThO2, with the balance being Fe. For example, one Ticomposition may include 15.0-23.0% Cr, 0.5-2.0% Si, 0.0-4.0% Mo,0.0-1.2% Nb, 0.0-3.0% Fe, 0.0-0.5% Ti, 0.0-0.5% Al, 0.0-0.3% Mn,0.0-0.1% Zr, 0.0-0.035% Ce, 0.005-0.025% Mg, 0.0005-0.005% B, 0.005-0.3%C, 0.0-20.0% Co, balance Ni. Sample Ti-based feedstock componentincludes 0-45% metal powder; 15-40% binder; 0-10% Polymer (e.g.,thermoplastics and thermosets); surfactant 0-3%; lubricant 0-3%;sintering aid 0-1%. Another sample Ti-based feedstock component includesabout 62% TiH2 powder as a metal powder; about 29% naphthalene as abinder; about 2.1-2.3% polymer (e.g., EVA/epoxy); about 2.3% SURFONICN-100 ® as a Surfactant; lubricant is 1.5% stearic acid as a; about 0.4%silver as a sintering Aid. Examples of metal compounds include metalhydrides, such as TiH2, and intermetallics, such as TiAl and TiAl3. Aspecific instance of an alloy includes Ti-6Al, 4V, among others. Inanother embodiment, the metal powder comprises at least approximately45% of the volume of the feedstock, while in still another, it comprisesbetween approximately 54.6% and 70.0%. In addition, Ti—Al alloys mayconsists essentially of 32-38% of Al and the balance of Ti and contains0.005-0.20% of B, and the alloy which essentially consists of the abovequantities of Al and Ti and contains, in addition to the above quantityof B, up to 0.2% of C, up to 0.3% of 0 and/or up to 0.3% of N (providedthat 0+N add up to 0.4%) and c) 0.05-3.0% of Ni and/or 0.05-3.0% of Si,and the balance of Ti.

Parts are molded until they feel that the cavity has been filled. Bothmold design factors such as runner and gate size, gate placement,venting and molding parameters set on the molding machine affect themolded part. A helium Pycnometer can determine if there are voidstrapped inside the parts. During molding, you have a tool that can beused to measure the percent of theoretical density achieved on the“Green” or molded part. By crushing the measured “green” molded partback to powder, you can now confirm the percent of air (or voids)trapped in the molded part. To measure this, the density of the moldedpart should be measured in the helium Pycnometer and compared to thetheoretical density of the feedstock. Then, take the same molded partthat was used in the density test and crush it back to powder. If thisgranulate shows a density of more than 100% of that of the feedstock,then some of the primary binders have been lost during the moldingprocess. The molding process needs to be corrected because using thisprocess with a degraded feedstock will result in a larger shrinkage andresult in a part smaller than that desired. It is vital to be sure thatyour molded parts are completely filled before continuing themanufacturing process for debinding and sintering. The helium Pycnometerprovides this assurance. Primary debinding properly debound parts areextremely important to establish the correct sintering profile. Theprimary binder must be completely removed before attempting to start toremove the secondary binder as the secondary binder will travel throughthe pores created by the extraction of the primary binder. Primarydebinding techniques depend on the feedstock type used to make theparts. However the feedstock supplier knows the amount of primarybinders that have been added and should be removed before proceeding tothe next process step. The feedstock supplier provides a minimum “browndensity” that must be achieved before the parts can be moved into afurnace for final debinding and sintering. This minimum brown densitywill take into account that a small amount of the primary binder remnantmay be present and could be removed by a suitable hold during secondarydebinding and sintering. The sintering profile should be adjusted toremove the remaining small percent of primary binder before the removalof the secondary binder. Most external feedstock manufacturers provideonly a weight loss percent that should be obtained to define suitabledebinding. Solvent debound parts must be thoroughly dried, before thehelium Pycnometer is used to determine the “brown” density so that theremnant solvent in the part does not affect the measured density value.When the feedstock manufacturer gives you the theoretical density of the“brown” or debound part, can validate the percent of debinding that hasbeen achieved. Most Metal Injection Molding (MIM) operations todayperform the secondary debinding and sintering in the same operation.Every MIM molder has gates and runners left over from molding theirparts. So, you will be able to now re-use your gates and runners withconfidence that they will shrink correctly after sintering. If thefeedstock producers have given you the actual and theoretical densitiesof their feedstock, you can easily measure the densities of the gatesand runners and compare the results to the values supplied. Once theregrind densities are higher than that required to maintain the partdimensions, the regrinds are no longer reusable.

Feedstock in accordance with the present invention may be prepared byblending the powdered metal with the binder and heating the blend toform a slurry. Uniform dispersion of the powdered metal in the slurrymay be achieved by employing high shear mixing. The slurry may then becooled to ambient temperature and then granulated to provide thefeedstock for the metal injection molding.

The amount of powdered metal and binder in the feedstock may be selectedto optimize moldability while insuring acceptable green densities. Inone embodiment, the feedstock used for the metal injection moldingportion of the invention may include at least about 40 percent by weightpowdered metal, in another about 50 percent by weight powdered metal ormore. In one embodiment, the feedstock includes at least about 60percent by weight powdered metal, preferably about 65 percent by weightor more powdered metal. In yet another embodiment, the feedstockincludes at least about 75 percent by weight powdered metal. In yetanother embodiment, the feedstock includes at least about 80 percent byweight powdered metal. In yet another embodiment, the feedstock includesat least about 85 percent by weight powdered metal. In yet anotherembodiment, the feedstock includes at least about 90 percent by weightpowdered metal.

The binding agent may be any suitable binding agent that does notdestroy or interfere with the powdered metals. The binder may be presentin an amount of about 50 percent or less by weight of the feedstock. Inone embodiment, the binder is present in an amount ranging from 10percent to about 50 percent by weight. In another embodiment, the binderis present in an amount of about 25 percent to about 50 percent byweight of the feedstock. In another embodiment, the binder is present inan amount of about 30 percent to about 40 percent by weight of thefeedstock. In one embodiment, the binder is an aqueous binder. Inanother embodiment, the binder is an organic-based binder. Examples ofbinders include, but are not limited to, thermoplastic resins, waxes,and combinations thereof. Non-limiting examples of thermoplastic resinsinclude polyolefins such as acrylic polyethylene, polypropylene,polystyrene, polyvinyl chloride, polyethylene carbonate, polyethyleneglycol, and mixtures thereof. Suitable waxes include, but are notlimited to, microcrystalline wax, bee wax, synthetic wax, andcombinations thereof.

Examples of suitable powdered metals for use in the feedstock include,but are not limited to: stainless steel including martensitic andaustenitic stainless steel, steel alloys, tungsten alloys, soft magneticalloys such as iron, iron-silicon, electrical steel, iron-nickel(50Ni-50F3), low thermal expansion alloys, or combinations thereof. Inone embodiment, the powdered metal is a mixture of stainless steel,brass and tungsten alloy. The stainless steel used in the presentinvention may be any 1 series carbon steels, 2 series nickel steels, 3series nickel-chromium steels, 4 series molybdenum steels, serieschromium steels, 6 series chromium-vanadium steels, 7 series tungstensteels, 8 series nickel-chromium-molybdenum steels, or 9 seriessilicon-manganese steels, e.g., 102, 174, 201, 202, 300, 302, 303, 304,308, 309, 316, 316L, 316Ti, 321, 405, 408, 409, 410, 416, 420, 430, 439,440, 446 or 601-665 grade stainless steel.

As known to those of ordinary skill in the art, stainless steel is analloy of iron and at least one other component that imparts corrosionresistance. As such, in one embodiment, the stainless steel is an alloyof iron and at least one of chromium, nickel, silicon, molybdenum, ormixtures thereof. Examples of such alloys include, but are not limitedto, an alloy containing about 1.5 to about 2.5 percent nickel, no morethan about 0.5 percent molybdenum, no more than about 0.15 percentcarbon, and the balance iron with a density ranging from about 7 g/cm³to about 8 g/cm³; an alloy containing about 6 to about 8 percent nickel,no more than about 0.5 percent molybdenum, no more than about 0.15percent carbon, and the balance iron with a density ranging from about 7g/cm³ to about 8 g/cm³; an alloy containing about 0.5 to about 1 percentchromium, about 0.5 percent to about 1 percent nickel, no more thanabout 0.5 percent molybdenum, no more than about 0.2 percent carbon, andthe balance iron with a density ranging from about 7 g/cm³ to about 8g/cm³; an alloy containing about 2 to about 3 percent nickel, no morethan about 0.5 percent molybdenum, about 0.3 to about 0.6 percentcarbon, and the balance iron with a density ranging from about 7 g/cm³to about 8 g/cm³; an alloy containing about 6 to about 8 percent nickel,no more than about 0.5 percent molybdenum, about 0.2 to about 0.5percent carbon, and the balance iron with a density ranging from about 7g/cm³ to about 8 g/cm³; an alloy containing about 1 to about 1.6 percentchromium, about 0.5 percent or less nickel, no more than about 0.5percent molybdenum, about 0.9 to about 1.2 percent carbon, and thebalance iron with a density ranging from about 7 g/cm³ to about 8 g/cm³;and combinations thereof.

Suitable tungsten alloys include an alloy containing about 2.5 to about3.5 percent nickel, about 0.5 percent to about 2.5 percent copper oriron, and the balance tungsten with a density ranging from about 17.5g/cm³ to about 18.5 g/cm³; about 3 to about 4 percent nickel, about 94percent tungsten, and the balance copper or iron with a density rangingfrom about 17.5 g/cm³ to about 18.5 g/cm³; and mixtures thereof.

In addition, the binders may contain additives such as antioxidants,coupling agents, surfactants, elasticizing agents, dispersants, andlubricants as disclosed in U.S. Pat. No. 5,950,063, which is herebyincorporated by reference in its entirety. Suitable examples ofantioxidants include, but are not limited to thermal stabilizers, metaldeactivators, or combinations thereof. In one embodiment, the binderincludes about 0.1 to about 2.5 percent by weight of the binder of anantioxidant. Coupling agents may include but are not limited totitanate, aluminate, silane, or combinations thereof. Typical levelsrange between 0.5 and 15% by weight of the binder.

The polymeric and composite casing components may be injection molded.Polymeric materials for the bullet-end and middle body components musthave propellant compatibility and resistance to gun cleaning solventsand grease, as well as resistance to chemical, biological andradiological agents. The polymeric materials must have a temperatureresistance higher than the cook-off temperature of the propellant,typically about 320° F. The polymeric materials must haveelongation-to-break values that to resist deformation under interiorballistic pressure as high as 60,000 psi in all environments(temperatures from about −65 to about 320° F. and humidity from 0 to100% relative humidity). According to one embodiment, the middle bodycomponent is either molded onto or snap-fit to the casing head-endcomponent after which the bullet-end component is snap-fit orinterference fit to the middle body component. The components may beformed from high-strength polymer, composite or ceramic.

Examples of suitable high strength polymers include composite polymermaterial including a tungsten metal powder, nylon 6/6, nylon 6, andglass fibers; and a specific gravity in a range of 3-10. The tungstenmetal powder may be 50%-96% of a weight of the bullet body. The polymermaterial also includes about 0.5-15%, preferably about 1-12%, and mostpreferably about 2-9% by weight, of nylon 6/6, about 0.5-15%, preferablyabout 1-12%, and most preferably about 2-9% by weight, of nylon 6, andabout 0.5-15%, preferably about 1-12%, and most preferably about 2-9% byweight, of glass fibers. It is most suitable that each of theseingredients be included in amounts less than 10% by weight. Thecartridge casing body may be made of a modified ZYTEL® resin, availablefrom E.I. DuPont De Nemours Co., a modified 612 nylon resin, modified toincrease elastic response.

Examples of suitable polymers include polyurethane prepolymer,cellulose, fluoro-polymer, ethylene inter-polymer alloy elastomer,ethylene vinyl acetate, nylon, polyether imide, polyester elastomer,polyester sulfone, polyphenyl amide, polypropylene, polyvinylidenefluoride or thermoset polyurea elastomer, acrylics, homopolymers,acetates, copolymers, acrylonitrile-butadinen-styrene, thermoplasticfluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates,polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates,polybutylene, terephthalates, polyether imides, polyether sulfones,thermoplastic polyimides, thermoplastic polyurethanes, polyphenylenesulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides,styrene acrylonitriles, polystyrenes, polyphenylene, ether blends,styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates,epoxies, phenolics, unsaturated polyesters, bismaleimides,polyurethanes, silicones, vinylesters, or urethane hybrids. Examples ofsuitable polymers also include aliphatic or aromatic polyamide,polyeitherimide, polysulfone, polyphenylsulfone, poly-phenylene oxide,liquid crystalline polymer and polyketone. Examples of suitablecomposites include polymers such as polyphenylsulfone reinforced withbetween about 30 and about 70 weight percent, and preferably up to about65 weight percent of one or more reinforcing materials selected fromglass fiber, ceramic fiber, carbon fiber, mineral fillers, organonanoclay, or carbon nanotube. Preferred reinforcing materials, such aschopped surface-treated E-glass fibers provide flow characteristics atthe above-described loadings comparable to unfilled polymers to providea desirable combination of strength and flow characteristics that permitthe molding of head-end components. Composite components can be formedby machining or injection molding. Finally, the cartridge case mustretain sufficient joint strength at cook-off temperatures. Morespecifically, polymers suitable for molding of the projectile-endcomponent have one or more of the following properties: Yield or tensilestrength at −65° F.>10,000 psi Elongation-to-break at −65° F.>15% Yieldor tensile strength at 73° F.>8,000 psi Elongation-to-break at 73°F.>50% Yield or tensile strength at 320° F.>4,000 psiElongation-to-break at 320° F.>80%. Polymers suitable for molding of themiddle-body component have one or more of the following properties:Yield or tensile strength at −65° F.>10,000 psi Yield or tensilestrength at 73° F.>8,000 psi Yield or tensile strength at 320° F.>4,000psi.

Commercially available polymers suitable for use in the presentinvention thus include polyphenylsulfones; copolymers ofpolyphenylsulfones with polyether-sulfones or polysulfones; copolymersand blends of polyphenylsulfones with polysiloxanes;poly(etherimide-siloxane); copolymers and blends of polyetherimides andpolysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers; and the like. Particularlypreferred are polyphenylsulfones and their copolymers with poly-sulfonesor polysiloxane that have high tensile strength and elongation-to-breakto sustain the deformation under high interior ballistic pressure. Suchpolymers are commercially available, for example, RADEL® R5800polyphenylesulfone from Solvay Advanced Polymers. The polymer can beformulated with up to about 10 wt % of one or more additives selectedfrom internal mold release agents, heat stabilizers, anti-static agents,colorants, impact modifiers and UV stabilizers.

The polymers of the present invention can also be used for conventionaltwo-piece metal-plastic hybrid cartridge case designs and conventionalshotgun shell designs. One example of such a design is an ammunitioncartridge with a one-piece substantially cylindrical polymeric cartridgecasing body with an open projectile-end and an end opposing theprojectile-end with a male or female coupling element; and a cylindricalmetal cartridge casing head-end component with an essentially closedbase end with a primer hole opposite an open end having a couplingelement that is a mate for the coupling element on the opposing end ofthe polymeric cartridge casing body joining the open end of the head-endcomponent to the opposing end of the polymeric cartridge casing body.The high polymer ductility permits the casing to resist breakage.

One embodiment includes a 2 cavity prototype mold having an upperportion and a base portion for a 5.56 case having a metal insertover-molded with a Nylon 6 (polymer) based material. In this embodimentthe polymer in the base includes a lip or flange to extract the casefrom the weapon. One 2-cavity prototype mold to produce the upperportion of the 5.56 case can be made using a stripper plate tool usingan Osco hot spur and two subgates per cavity. Another embodimentincludes a subsonic version, the difference from the standard and thesubsonic version is the walls are thicker thus requiring less powder.This will decrease the velocity of the bullet thus creating a subsonicround.

The extracting inserts is used to give the polymer case a tough enoughridge and groove for the weapons extractor to grab and pull the case outthe chamber of the gun. The extracting insert is made of 17-4 stainlesssteel that is hardened to 42-45rc. The insert may be made of aluminum,brass, cooper, steel or even an engineered resin with enough tensilestrength.

The insert is over molded in an injection molded process using a nanoclay particle filled Nylon material. The inserts can be machined orstamped. In addition, an engineered resin able to withstand the demandon the insert allows injection molded and/or even transfer molded.

One of ordinary skill in the art will know that many propellant typesand weights can be used to prepare workable ammunition and that suchloads may be determined by a careful trial including initial lowquantity loading of a given propellant and the well known stepwiseincreasing of a given propellant loading until a maximum acceptable loadis achieved. Extreme care and caution is advised in evaluating newloads. The propellants available have various burn rates and must becarefully chosen so that a safe load is devised.

The components may be made of polymeric compositions, metals, ceramics,alloys, or combinations and mixtures thereof. In addition, thecomponents may be mixed and matched with one or more components beingmade of different materials. For example, the middle body component (notshown) may be polymeric; the bullet-end component 18 may be polymeric;and a substantially cylindrical insert (not shown) may be metal.Similarly, the middle body component (not shown) may be polymeric; thebullet-end component 18 may be metal; and a substantially cylindricalinsert (not shown) may be an alloy. The middle body component (notshown) may be polymeric; the bullet-end component 18 may be an alloy;and a substantially cylindrical insert (not shown) may be an alloy. Themiddle body component (not shown); the bullet-end component 18; and/orthe substantially cylindrical insert may be made of a metal that isformed by a metal injection molding process.

FIG. 14 depicts an exploded view of the polymeric cartridge casing. Acartridge 10 suitable for use with high velocity rifles is shownmanufactured with a middle body component 28 having a substantiallycylindrical open-ended polymeric bullet-end 18 extending from forwardend opening 16 rearward to opposite end 20. A portion of a cartridgesuitable for use with high velocity rifles is shown manufactured with apolymer casing 12 showing a powder chamber 14. The polymer casing 12 hasa substantially cylindrical opposite end 20. The bullet-end component 18may be formed with the coupling end 22 formed on end 20. The couplingend 22 is shown as a female element, but may also be configured as amale element in alternate embodiments of the invention. The middle bodycomponent 28 is connected to a substantially cylindrical couplingelement 30 of the substantially cylindrical insert 32. The substantiallycylindrical open-ended polymeric bullet-end 18 has a shoulder 24 formingchamber neck 26 and a bullet 56 inserted therein. The substantiallycylindrical insert 32 also has a flange 46 cut therein and a primerrecess (not shown) formed therein for ease of insertion of the primer(not shown). When contacted the coupling end 22 interlocks with thesubstantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32and middle body component 28. In one embodiment of the presentinvention, the substantially cylindrical insert 32 may be made of ametal that is formed by a metal injection molding process. The modeldesign may be seen herein.

The molded substantially cylindrical insert 32 is then bound to themiddle body component 28. In the metal injection molding process ofmaking the substantially cylindrical insert 32 a mold is made in theshape of the substantially cylindrical insert 32 including the desiredprofile of the primer recess (not shown). The substantially cylindricalinsert 32 includes a substantially cylindrical coupling element 30extending from a bottom surface 34 that is opposite a top surface (notshown). Located in the top surface (not shown) is a primer recess (notshown) that extends toward the bottom surface 34. A primer flash hole(not shown). is located in the substantially cylindrical insert 32 andextends through the bottom surface 34 into the powder chamber 14. Thecoupling end (not shown) extends through the primer flash hole (notshown) to form an aperture coating (not shown) while retaining a passagefrom the top surface (not shown) through the bottom surface (not shown)and into the powder chamber 14 to provides support and protection aboutthe primer flash hole (not shown). When contacted the coupling end (notshown) interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip (not shown) to form a physical interlockbetween substantially cylindrical insert 32 and middle body component28.

For example, the metal injection molding process, which generallyinvolves mixing fine metal powders with binders to form a feedstock thatis injection molded into a closed mold, may be used to form asubstantially cylindrical insert. After ejection from the mold, thebinders are chemically or thermally removed from the substantiallycylindrical insert so that the part can be sintered to high density.During the sintering process, the individual metal particlesmetallurgically bond together as material diffusion occurs to removemost of the porosity left by the removal of the binder.

The raw materials for metal injection molding are metal powders and athermoplastic binder. There are at least two Binders included in theblend, a primary binder and a secondary binder. This blended powder mixis worked into the plasticized binder at elevated temperature in akneader or shear roll extruder. The intermediate product is theso-called feedstock. It is usually granulated with granule sizes ofseveral millimeters. In metal injection molding, only the binders areheated up, and that is how the metal is carried into the mold cavity.

FIGS. 15A and 15B depict a view of the substantially cylindricalopen-ended polymeric bullet-end having a shoulder forming chamber neckand a bullet. FIGS. 15A and 15B depict show the substantiallycylindrical open-ended polymeric bullet-end 18 has a shoulder 24 formingchamber neck 26 and a bullet (not shown). One embodiment includesmodifications to strengthen the neck of the mouth 60 and to the internalbase area 62 to reduce nose tearing and lodging in the chamber. Thesubstantially cylindrical open-ended polymeric bullet-end 18 illustratesa lock 58 (e.g., 0.030×0.003) and added a step to allow for the lock 58to flex out during firing. The polymer was added to the external area tostrengthen the neck of the mouth 60 and to the internal base area 62.The interference of the bullet to the neck was increased by adding thepolymer to the inside of the neck 64 and the exit lock modified byadding an angle to the rim 66.

FIG. 16 depicts an elevation view of a bullet-end component of thepolymeric cartridge casing. A cartridge (not shown) suitable for usewith high velocity rifles may be manufactured as a modular componentsystem with a middle body component (not shown) with one end beingconnected to a bullet-end component 18 that is connected to a bullet(not shown) inserted therein and the other end being connected to asubstantially cylindrical insert (not shown). As the cartridge (notshown) is made as a modular component system it must be assembled andfused together, e.g., the substantially cylindrical insert (not shown)must be attached to the middle body component (not shown) and thebullet-end component 18 must also be attached to the middle bodycomponent (not shown). In addition, the bullet (not shown) must beattached to the bullet-end component 18 at the forward end opening 16.The bullet-end component 18 has a shoulder 24 forming chamber neck 26and a forward end opening 16 at one end to receive a bullet (not shown)and a powder chamber coupling 68 at the other that mates to the powderchamber (not shown). The forward end opening 16 may include a texturedsurface 70 that extends into the inner neck 64 to enhance the sealing ofthe bullet (not shown) and the bullet-end component 18. The texturedsurface 70 may be in the form of groves, slots, channels, scratches orany other texture to increase the surface area to enhance bonding of thebullet (not shown) and the bullet-end component 18. For example, theforward end opening 16 may include a textured surface 70 of channelsthat extend into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. During assembly thetextured surface 70 provides additional surface area for the adhesive tointeract with and thus secure the seal between the bullet (not shown)and the forward end opening 16.

FIG. 17 depicts a side, cross-sectional view of a bullet-end componentof the polymeric cartridge casing. A cartridge (not shown) suitable foruse with high velocity rifles may be manufactured as a modular componentsystem with a middle body component (not shown) with one end beingconnected to a bullet-end component 18 that is connected to a bullet(not shown) inserted therein and the other end being connected to asubstantially cylindrical insert (not shown). The cartridge (not shown)is made as a modular component system it must be assembled and fusedtogether, e.g., the substantially cylindrical insert (not shown) must beattached to the middle body component (not shown) and the bullet-endcomponent 18 must also be attached to the middle body component (notshown). In addition, the bullet (not shown) must be attached to thebullet-end component 18 at the forward end opening 16. The bullet-endcomponent 18 has a shoulder 24 forming chamber neck 26 and a forward endopening 16 at one end to receive a bullet (not shown) and a powderchamber coupling 68 at the other that mates to the powder chamber (notshown). The forward end opening 16 may include a textured surface 70that extends into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. The textured surface 70 maybe in the form of groves, slots, channels, scratches or any othertexture to increase the surface area to enhance bonding of the bullet(not shown) and the bullet-end component 18. For example, the forwardend opening 16 may include a textured surface 70 of channels or groovesthat extend into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. During assembly thetextured surface 70 provides additional surface area for the adhesive tointeract with and thus secure the seal between the bullet (not shown)and the forward end opening 16. For example the textured surface 70 maybe grooves that extend into the inner neck 64 so that an adhesive whenapplied to the bullet can wick into the grooves and into the inner neck64 to provide a contact area on the bullet and the inner neck 64 for theadhesive. The adhesive can then be cured (e.g., UV light) and sealed.The textured surface 70 may be in any form that allows wicking and/orthe increasing of the surface area, e.g., hatching, grooves, scratches,roughness, etc.

The description of the preferred embodiments should be taken asillustrating, rather than as limiting, the present invention as definedby the claims. As will be readily appreciated, numerous combinations ofthe features set forth above can be utilized without departing from thepresent invention as set forth in the claims. Such variations are notregarded as a departure from the spirit and scope of the invention, andall such modifications are intended to be included within the scope ofthe following claims.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

What is claimed is:
 1. A method of making a polymer ammunition having aninjection molded primer insert comprising by the steps of: forming asubstantially cylindrical primer insert by injection molding from aprimer insert injection mold, wherein the substantially cylindricalprimer insert comprises a top surface opposite a bottom surface and asubstantially cylindrical coupling element that extends from the bottomsurface, a primer recess in the top surface that extends toward thebottom surface, a primer flash aperture positioned in the primer recessto extend through the bottom surface, a primer flash aperture groovepositioned in the primer recess around the primer flash aperture, aprimer flash aperture groove positioned in the primer recess around theprimer flash aperture, and a flange that extends circumferentially aboutan outer edge of the top surface; providing a first polymer compositionfor molding a polymer ammunition cartridge; molding from the firstpolymer composition a substantially cylindrical polymeric middle bodyhaving the substantially cylindrical primer insert at a first end and asubstantially cylindrical polymeric coupling region at a second end,wherein the first polymer composition extends over an outer surface ofthe substantially cylindrical primer insert to the flange and extendsover an interior surface of the substantially cylindrical couplingregion into the primer flash hole aperture and into the primer flashaperture groove, wherein the first polymer composition is overmoldedinto the primer flash hole aperture to form a flash hole the primerflash hole aperture; forming a substantially cylindrical polymericbullet-end component from a second polymer composition comprising abullet aperture opposite a polymeric bullet-end coupling that mates tothe substantially cylindrical coupling region; coupling thesubstantially cylindrical coupling region to the polymeric bullet-endcoupling to form a propellant chamber that extends from the primer flashhole aperture to the bullet aperture; inserting a primer diffuser intothe primer recess, wherein the primer diffuser comprises a diffuseraperture that aligns with the primer flash hole aperture and the primerflash hole; inserting a primer into the primer recess in contact withthe primer diffuser, wherein the primer is in operably communicationwith the propellant chamber through the primer flash hole aperture; atleast partially filling the propellant chamber with a propellant; andfrictionally fitting a projectile in the bullet-end aperture, whereinthe propellant chamber is enclosed at one end by the primer and theprojectile at the other end.
 2. The method of claim 1, wherein the firstpolymer composition is the same as the second polymer composition. 3.The method of claim 1, wherein the first polymer composition is aductile polymer.
 4. The method of claim 1, wherein the first polymercomposition, the second polymer composition or both comprise a nylonpolymer.
 5. The method of claim 1, wherein the first polymercomposition, the second polymer composition or both comprise afiber-reinforced polymeric composite.
 6. The method of claim 1, whereinthe first polymer composition, the second polymer composition or bothcomprise between about 10 and about 70 wt % glass fiber fillers, mineralfillers, or mixtures thereof.
 7. The method of claim 1, wherein thebullet aperture comprises one or more cannelures formed on an innercircumferential surface of the bullet aperture.
 8. The method of claim1, wherein the substantially cylindrical coupling region and thepolymeric bullet-end coupling are welded or bonded together.
 9. Themethod of claim 1, wherein the first polymer composition, the secondpolymer composition or both comprise polyurethane prepolymer, cellulose,fluoro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinylacetate, nylon, polyether imide, polyester elastomer, polyester sulfone,polyphenyl amide, polypropylene, polyvinylidene fluoride or thermosetpolyurea elastomer, acrylics, homopolymers, acetates, copolymers,acrylonitrile-butadinen-styrene, thermoplastic fluoro polymers, inomers,polyamides, polyamide-imides, polyacrylates, polyatherketones,polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene,terephthalates, polyether imides, polyether sulfones, thermoplasticpolyimides, thermoplastic polyurethanes, polyphenylene sulfides,polyethylene, polypropylene, polysulfones, polyvinylchlorides, styreneacrylonitriles, polystyrenes, polyphenylene, ether blends, styrenemaleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies,phenolics, unsaturated polyesters, bismaleimides, polyurethanes,silicones, vinylesters, urethane hybrids, polyphenylsulfones, copolymersof polyphenylsulfones with polyethersulfones or polysulfones, copolymersof poly-phenylsulfones with siloxanes, blends of polyphenylsulfones withpolysiloxanes, poly(etherimide-siloxane) copolymers, blends ofpolyetherimides and polysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers.
 10. The method of claim 1, furthercomprising a neck positioned between the bullet aperture and thepolymeric bullet-end coupling.
 11. The method of claim 10, furthercomprising one or more internal structures in the neck to support aprojectile.
 12. The method of claim 1, wherein the bullet aperturecomprises one, two, three, or more annular rings that mate with one,two, three, or more corresponding annular grooves positioned on theprojectile.
 13. The method of claim 1, wherein the injection moldedprimer insert comprises 2-16% Ni; 10-20% Cr; 0-5% Mo; 0-0.6% C; 0-6.0%Cu; 0-0.5% Nb+Ta; 0-4.0% Mn; 0-2.0% Si and the balance Fe.
 14. Themethod of claim 1, wherein the injection molded primer insert comprises2-6% Ni; 13.5-19.5% Cr; 0-0.10% C; 1-7.0% Cu; 0.05-0.65% Nb+Ta; 0-3.0%Mn; 0-3.0% Si and the balance Fe.
 15. The method of claim 1, wherein theinjection molded primer insert comprises 3-5% Ni; 15.5-17.5% Cr; 0-0.07%C; 3-5.0% Cu; 0.15-0.45% Nb+Ta; 0-1.0% Mn; 0-1.0% Si and the balance Fe.16. The method of claim 1, wherein the injection molded primer insertcomprises 10-14% Ni; 16-18% Cr; 2-3% Mo; 0-0.03% C; 0-2% Mn; 0-1% Si andthe balance Fe.
 17. The method of claim 1, wherein the injection moldedprimer insert comprises 12-14% Cr; 0.15-0.4% C; 0-1% Mn; 0-1% Si and thebalance Fe.
 18. The method of claim 1, wherein the injection moldedprimer insert comprises 16-18% Cr; 0-0.05% C; 0-1% Mn; 0-1% Si and thebalance Fe.
 19. The method of claim 1, wherein the injection moldedprimer insert comprises 3-12% aluminum, 2-8% vanadium, 0.1-0.75% iron,0.1-0.5% oxygen, and the remainder titanium.
 20. The method of claim 1,wherein the injection molded primer insert comprises about 6% aluminum,about 4% vanadium, about 0.25% iron, about 0.2% oxygen, and theremainder titanium.
 21. A method of making a polymer ammunition havingan injection molded primer insert comprising by the steps of: forming asubstantially cylindrical primer insert by injection molding from aprimer insert injection mold, wherein the substantially cylindricalprimer insert comprises a top surface opposite a bottom surface and asubstantially cylindrical coupling element that extends from the bottomsurface, a primer recess in the top surface that extends toward thebottom surface, a primer flash aperture positioned in the primer recessto extend through the bottom surface, a primer flash aperture groovepositioned in the primer recess around the primer flash aperture, and aflange that extends circumferentially about an outer edge of the topsurface; providing a first polymer composition for molding a polymerammunition cartridge; molding from the first polymer composition to formover the substantially cylindrical primer insert to form a substantiallycylindrical polymeric middle body having the overmolded substantiallycylindrical primer insert at a first end and a substantially cylindricalpolymeric coupling region at a second end, wherein the first polymercomposition extends over an outer surface of the substantiallycylindrical primer insert to the flange and extends over an interiorsurface of the substantially cylindrical coupling region into the primerflash hole aperture and into the primer flash aperture groove to form aflash hole, wherein the first polymer composition extends from thesubstantially cylindrical polymeric coupling region to the primer flashaperture groove to form a flash hole; forming a substantiallycylindrical polymeric bullet-end component from a second polymercomposition comprising a bullet aperture opposite a polymeric bullet-endcoupling that mates to the substantially cylindrical coupling region,and a neck positioned between the bullet aperture and the polymericbullet-end coupling; coupling the substantially cylindrical couplingregion to the polymeric bullet-end coupling to form a propellant chamberthat extends from the primer flash hole aperture to the bullet aperture;inserting a primer diffuser into the primer recess, wherein the primerdiffuser comprises a diffuser aperture that aligns with the primer flashhole aperture and the primer flash hole; inserting a primer into theprimer recess, wherein the primer is in operably communication with thepropellant chamber through the primer flash hole aperture; at leastpartially filling the propellant chamber with a propellant; andfrictionally fitting a projectile in the bullet-end aperture, whereinthe propellant chamber is enclosed at one end by the primer and theprojectile at the other end.